SOME time in 1980, during the five months that the grim and glorious musical “Sweeney Todd” played the Theater Royal Drury Lane, a California college student visiting London bought a ticket. And another and another and another.

Tim Burton, obsessive watcher of horror movies and a worshiper of Vincent Price, had discovered “The Demon Barber of Fleet Street,” not to mention Stephen Sondheim. And after stewing in his imagination on and off for some 25 years, that encounter has been channeled into Mr. Burton’s new film version, scheduled to arrive Dec. 21, with Johnny Depp as Sweeney, Helena Bonham Carter as Mrs. Lovett and the smoke-blackened streets of Victorian London as the setting for their danse macabre.

Any way you slice it, it’s a gamble.

Transferring a stage work to the screen is always dodgy; for musicals, so dependent on the artificial world of the proscenium, the risks are multiplied. To further complicate things Mr. Burton entrusted the lead roles in this operatic, difficult-to-sing work, which scooped up no less than eight Tony Awards in 1979, to two movie stars whose vocal abilities, like those of all but one of the supporting players, were untested. (They include Sacha Baron Cohen, as the competing barber Pirelli.)

There’s also the little matter of the R-rated plot, which revels in the throat-cutting, meat-chopping proclivities of a serial killer whose victims are funneled from a trick barber’s chair into a giant meat grinder, processed and then baked into tasty little meat pies by his cooperative landlady.

Even less bloody shows by Mr. Sondheim have not been served well by the movies. Some — “Pacific Overtures,” say, “Sunday in the Park With George” or “Assassins”— are so intrinsically theatrical in conception that they seem virtually unfilmable. Of the others for which he has also written both music and lyrics, only two, “A Funny Thing Happened on the Way to the Forum” (1966) and “A Little Night Music” (1978), had made it to celluloid (and not very happily) before Mr. Burton tackled “Sweeney.”

“Sweeney Todd: The Demon Barber of Fleet Street” may seem a more likely candidate for film success, given its origins in melodrama and Grand Guignol, the slasher movies of the 19th century. Still, “It took courage and a certain lunatic leap of faith to think we could really bring this wild beast to the screen,” the screenwriter, John Logan, said via e-mail.

Mr. Burton was not making films when he first saw “Sweeney Todd.” But he was struck, he recalled in a recent telephone interview, by how cinematic it was. Propelled by Mr. Sondheim’s extensive underscoring, Harold Prince’s production flowed from scene to scene within a cavernous metal cage, using revolving set pieces housing Mrs. Lovett’s pie shop, Sweeney’s tonsorial establishment and the show’s other locations. When Mr. Burton’s film career took off, in the late ’80s, he approached Mr. Sondheim about a film .

“I said fine,” Mr. Sondheim said by telephone recently. “Then he went off and did other things.”

Mr. Burton explained, “You get sort of sidetracked.” But, he said, it was all for the best. “Back then, I didn’t really know Johnny.” And he hadn’t yet met Ms. Bonham Carter, with whom he now lives. (They are expecting their second child next month.)

Around five years ago, he said, he stumbled on an old drawing he had made of Sweeney Todd and Mrs. Lovett. To his surprise, “they kind of looked like Johnny and Helena.” The wheels began to turn. “Those kinds of things mean something to me,” Mr. Burton said. “Johnny had gotten to the point where he was the right age. There was something about it that felt really right, even though I didn’t know if he could sing.”

He gave Mr. Depp the album and asked, “Would you ever think about doing something like this?” He said Mr. Depp listened and responded, “I may sound like a strangled cat.” Mr. Burton took that as a yes. “If he didn’t think he could do it, he would have said no.”

Mr. Burton and Mr. Depp had already created a gallery of memorable weirdos, starting in 1990 with the unfortunate adolescent of “Edward Scissorhands” and continuing with the transvestite film director at the center of “Ed Wood” and the oddly epicene Willy Wonka in “Charlie and the Chocolate Factory.” Mr. Depp’s Sweeney isn’t a regular guy either. With a Susan Sontag patch of white streaking his pompadour, ghostly skin and distraught eyes, this Sweeney is both wretched and mad. “He needed to have a look that would say a lot about what he’d been through,” Mr. Depp said by telephone.

Photo

Tim Burton on the set of his film version of Stephen Sondheims musical Sweeney Todd.Credit
Peter Mountain/Paramount Pictures

What he’d been through, what turned him into a revenge machine, was a trumped-up conviction that enabled an evil judge (played by Alan Rickman) to destroy his family. Mr. Burton’s take on the material had been formed when he’d seen the London production. “I always felt it was like a silent movie with music in it — those old black and white horror movies.”

He talked with Mr. Depp, also a silents fan, about the approach; their touchstones were Lon Chaney, Boris Karloff, Bela Lugosi and Peter Lorre, especially, Mr. Depp said, Lorre’s “creepy but sympathetic” surgeon in the 1935 thriller “Mad Love.” The influence of silent film permeates the movie, from the chiaroscuro lighting to the we-had-faces close-ups. “Johnny in front of his victims with the razor is almost like a ballet dancer, dancing around them,” said Richard D. Zanuck, a producer.

Mr. Burton asked the designer, Dante Ferretti, to recreate not Victorian London but horror-movie London. Mr. Ferretti, who began his career working with Fellini, first visited the relevant neighborhoods around Fleet Street, he said. “Then we did it a little bit more frightening, more dark, more interesting.”

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Initially Mr. Burton had planned to make the film with few sets and lots of computerized effects. He ended up doing just the opposite. “This is a musical,” he said. “Having sets helps you, it helps the actors, it helps the crew get into the right frame of mind. Just having people singing in front of a green screen seemed more disconnected.”

Mr. Depp began performing in rock bands as a teenager. But “never, ever, did I ever want to sing,” he insisted. “Singers always got too much attention. I was always happier playing my guitar in the dark.”

The plan was for him to work with a vocal coach, “do the scales and all that stuff.” But “it started to dawn on me that I knew what Sweeney sounded like before, and I knew that it was up to me to go far away from that,” he said. “He needed to be, for lack of a better word, slightly more punk rock.”

He studied the songs as he was filming the third installment of the “Pirates of the Caribbean” series in Palmdale, Calif. — “two hours to work and two hours back listening constantly, learning the melodies in the car.”

Mike Higham, the film’s music producer, said that isn’t quite as easy as it sounds. “With Stephen’s music the melodies don’t roll off the tongue,” he said. “They run around the scale. It’s hard for actors to get into the pockets of where the music really is.”

Part of Mr. Higham’s job was cutting the music to fit the film, which follows closely the contours of the original show. Mr. Sondheim summed up the operative principle: “In the theater you can sing for three or four minutes even though there’s nothing happening. On film you want to keep things moving.”

Some songs, including the show’s framing number, “The Ballad of Sweeney Todd,” were cut. Others, like “Green Finch and Linnet Bird” and “God, That’s Good!” were shortened. Mr. Higham sent his changes to Mr. Sondheim as MP3 files. “Then he might say, ‘That’s O.K.,’ or ‘Change that F sharp to a B flat,’” Mr. Higham said.

Mr. Sondheim’s longtime orchestrater, Jonathan Tunick, augmented the orchestra from 27 musicians in the original Broadway production to 78, “to get the big cinematic sound Tim was after,” Mr. Higham said.

Like Mr. Ferretti and Mr. Depp, Mr. Higham noted how economically Mr. Burton conveyed his thoughts. “He can say three words, and he completely sums up what his vision is,” he said. “You get those three words, and you go.” For “Sweeney,” Mr. Higham said, Mr. Burton’s words were, “I want the music almost not to stop.”

While Mr. Depp and the rest of the cast were finding their way into the music, Mr. Burton was finding his way into the gore. “He had a very clear plan that he wanted to lift that up into a surreal, almost ‘Kill Bill’ kind of stylization,” Mr. Zanuck said. “We had done tests and experiments with the neck slashing, with the blood popping out. I remember saying to Tim, ‘My god, do we dare do this?’ ”

The results worked, at least according to Mr. Depp. The red liquid latex his razor sent spurting from the necks of Sweeney’s victims during the 50-day shoot last winter was, well, thicker than water. “You see it, you feel it, you hear it,” he said. “It wasn’t subtle.”

Correction: November 18, 2007

An article on Nov. 4 in the Holiday Movies section about the film adaptation of “Sweeney Todd” misstated the number of Tony Awards that musical won for its original Broadway run in 1979. It was eight, not seven.

A version of this article appears in print on , on Page 26 of the New York edition with the headline: Demon Barber, Meat Pies and All, Sings on Screen. Order Reprints|Today's Paper|Subscribe